With increasing development of science and technology, electronic devices become more and more popular to personal users. The widely-used electronic device includes for example a computer host, a notebook computer, a mobile phone or any other appropriate portable electronic device. Moreover, a peripheral input device may be cooperatively used with the electronic device in order to enhance the operating flexibility of the electronic device. The peripheral input device includes for example a mouse device, a keyboard device or a trackball device.
Generally, a membrane switch circuit has to be installed in the keyboard device. When the membrane switch circuit is pressed by a key of the keyboard device, a corresponding key signal is outputted from the membrane switch circuit. Consequently, the user may input letters, numbers or symbols via the keyboard device. Generally, in the fabrication of the keyboard device, a testing method should be performed to realize whether the functions of the keyboard device are normal or not. The testing method comprises a procedure of testing a circuit board and the membrane switch circuit before the keyboard device is assembled and further comprises a procedure of testing the overall functions of the assembled keyboard device. By testing the circuit board and the membrane switch circuit, the manufacturer may realize whether there is any defect in the circuit board or the membrane switch circuit before the keyboard device is assembled. If the procedures of testing the circuit board and the membrane switch circuit are not done and some defects are found after the keyboard device is assembled, the manufacturer needs to disassemble the keyboard device to debug the circuit board and the membrane switch circuit. It is time-consuming to disassemble the electronic device and debug the circuit board and the membrane switch circuit.
The subject of the present invention is directed to a testing system of a membrane switch circuit. Hereinafter, the structure of a membrane switch circuit will be illustrated with reference to FIG. 1. FIG. 1 is a schematic exploded view illustrating a conventional membrane switch circuit. The conventional membrane switch circuit 1 comprises an upper wiring board 11, a spacer layer 12, and a lower wiring board 13. The upper wiring board 11 has plural first contacts 111 corresponding to plural keys (not shown) of the keyboard device (not shown). The spacer layer 12 is disposed under the upper wiring board 11, and comprises plural perforations 121 corresponding to the plural first contacts 111. The lower wiring board 13 is disposed under the spacer layer 12, and comprises plural second contacts 131 corresponding to the plural first contacts 111. After the upper wiring board 11, the spacer layer 12 and the lower wiring board 13 are combined together, the plural first contacts 111 are disposed over the plural perforations 121, and the plural second contacts 131 are disposed under the plural perforations 121. Each of the plural first contacts 111, the corresponding perforation 121 and the corresponding second contact 131 are collectively defined as a key intersection. The key intersection has an intersection resistance value.
When one of the plural keys is depressed by the user, the first contact 111 of the upper wiring board 11 under the depressed key is pushed and inserted into the corresponding perforation 121, and the first contact 111 is contacted with the corresponding second contact 131. Meanwhile, a corresponding key signal is outputted from the membrane switch circuit 1. When the key is no longer depressed, the first contact 111 and the corresponding second contact 131 are separated from each other, and the first contact 111 and the corresponding second contact 131 are partitioned by the spacer layer 12. Consequently, the first contact 111 and the corresponding second contact 131 are not erroneously connected with each other. However, when the first contact 111 and the corresponding second contact 131 are contacted with each other, if the intersection resistance value is very large, the membrane switch circuit 1 fails to generate the key signal. For solving the above drawbacks, it is necessary to test the key intersections before the keyboard device is assembled.
Generally, an exclusive membrane switch circuit testing fixture and a computer system are employed to test the membrane switch circuit. The testing fixture comprises a resistance meter. Then, all key intersections of the membrane switch circuit may be sequentially pressed by the tester or by using a knocking tool. Consequently, plural intersection resistance values of the plural key intersections are sequentially acquired by the resistance meter. However, the conventional testing method still has some drawbacks. For example, since plural intersection resistance values are transmitted from the resistance meter to the computer system, the tester cannot recognize which intersection resistance values are relevant to specified key intersections. In other words, the sequence of depressing the key intersections has to be recorded or previously arranged by the tester, and then the sequence of depressing the key intersections is correlated with the corresponding intersection resistance values by the tester. Consequently, the tester can recognize which key intersection has the larger intersection resistance value in order to implement associated adjustment.
After the membrane switch circuit is manually tested for a long time, the tester may often erroneously judge the testing result. Under this circumstance, the key intersections are erroneously correlated with the intersection resistance values, and thus the testing accuracy is impaired.
Therefore, there is a need of providing a membrane switch circuit testing system without the manual measurement.